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    <script>
        /* 打印99乘法表 */
        var printStr = '';
        for(var i = 1;i<=9;i++){
            for(var j = 1;j<=i;j++){
                //外部循环几次，内部就循环几次
                printStr +=i+"x"+j+"="+i*j+"\t";
            }
            printStr+="\n";
        }
        console.log(printStr);
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